Why would you bet your own money when you could bet someone else’s?

If you are betting on a winner why split with others?

If you know the winner, it’s not gambling. Self-driving cars are still a gamble.

risk management. Even sure thing bets lose money once in a while, so it is a good idea to spread the risk of that around.

Alphabet is only giving up around a 3% stake. They continue to own most of it, and mostly bet their own money.